@Rentero - LiveATC has an ATC Audio Archive link where you can access past recordings, I was able to find where one of the pilots is checking in with MMMY Departure (callsign is November 345 Mike Charlie - N345MC) at about 19min and 34secs into the recording, he is at 3000 feet and requesting 37,000 feet (FL370), departure clears him to FL370 and then at about 23min and 49secs departure hands him over to the next ATC frequency 124.5 Mhz which is not covered on this feed so it is the last we hear from them. (To access recorded feed click ATC Audio Archive on left link menu on LiveATC homepage, choose UTC date Sunday Dec. 9th, 2012, MMMY (Monterrey) and 0900z-0930z GMT/UTC time)

"MEXICO CITY — The plane carrying Mexican-American music superstar Jenni Rivera plunged almost vertically from more than 28,000 feet and hit the ground in a nose-dive at a speed that may have exceeded 600 miles per hour, Mexico's top transportation official said Tuesday.

In the first detailed account of the moments leading up to the crash that killed Rivera and six other people, Secretary of Communications and Transportation Gerardo Ruiz Esparza told Radio Formula that the twin-engine turbojet hit the ground 1.2 miles from where it began falling"

Thanks for the link joeyb747, really horrible event, the plane had to have either a total loss of hydraulic and electrical power (in which case the pilots could not control the flight surfaces, communicate with ATC and declare an Emergency), or a total loss of cabin pressure as it was still climbing to FL370(in which case everyone loss consciousness if oxygen masks did not deploy) and still under manual control, in order to fall out of the sky at that altitude (FL280) and speed (600mph+) ... my only other conclusion is sabatoge such as a time bomb or exploding device onboard, the singer had allegedly received death threats in the past by Mexican crime syndicates ... really horrible situation.

UPDATE: According to the latest reports on Mexican TV there appears to be no signs of fire or burning at the wreckage which most likely indicates that the plane's fuel either had completely run out, or had leaked out somehow without either of the pilots' knowledge, The human remains and personal items found do not appear to be burnt or charred, neither are any of the pieces of the plane. The pilots still should of been able to make a Mayday call if they still had electrical power and were not in a panicked state .... awful

I believe the Lear only uses hydraulics for the spoilers, everything else being cabled. Sounds to me more like explosive decompression or fan failure with damage to the empennage, cables or trim system.

@InterpreDemon - Interesting point, does that apply to all Learjets or just the ones made before a certain year ? The fact that there was no fire after impact still points to no fuel onboard though.. I'm assuming that the jet was supposed to be fully, or near, fully fueled as the trip was estimated to take at least 1 hour and 20 min, and it disappeared from radar about 10 min after takeoff.

Yeah, but planes that run out of fuel do not just lawn dart into the ground. If they had a fan explosion it could have taken out both engines, or the pilot shut the other down due to vibration or confusion. The idea that they were dumping fuel without knowing it to the point of exhaustion in such a short period and not having time to declare an emergency before the cabin completely de-pressurized seems a tad far fetched to me. That's a plane that can go to FL450 and the pilots are very aware of emergency procedures like donning oxy immediately. No, either it had to be something that immediately rendered the aircraft uncontrollable or the pressurization system was not operating throughout the climb (which that plane can do like few others not armed with missiles) and they got confused and passed out before they knew what was happening. Even in that scenario they would have had to be flying manually and not on AP or the FMC because otherwise fighters would have been dispatched to follow the plane until it ran out of fuel and fell from the sky.

@InterpreDemon - Yes I agree, also I think the pilots should of been able to at least "glide" the plane down somewhere between the mountains (as it would essentially become a glider if all thrust is gone), provided they were conscious and had some flight surface control, and being they were at least 28,000 feet, they should of had plenty of time for a crash landing ... now the fact that the Secretary and Minister of Transportation in Mexico is saying that the plane almost completely nose dived and crashed means it was a far more serious situation on that flight ... (click link below)